Second order average current nodal expansion method for time-dependent neutron diffusion simulation

In the present work, a timedependent neutron diffusion simulator is developed utilizing the second order of average current nodal expansion method. Generally, nodal methods can accurately simulate the reactor core with coarse meshes as long as the sizes of a fuel assembly. In this case, an adopted iterative approach is used for resolving the timedependent threedimensional multigroup neutron balance equations coupled with sixgroup precursor equations. In order to evaluate the implemented methodology, two popular transient problems are used including TWIGL twodimensional seedblanket reactor and threedimensional LMW LWR. For indicating the precision of the method, the numerical results of high (second) order approach also have been compared with the basic methodology i.e. the zeroth order solution. From the comparison of obtained results with references, the suitable and precise simulating of transient schemes can be comprehended using the timedependent second order average current nodal expansion method. Moreover, the results confirm that the second order solution can treat the coarse mesh dynamic problems with more accuracy relative to the basic approach.